Pneumatic feed for gas lifts



Nov. 29, 1949 c. M. O'LEARY 2,489,665

PNEUMATIG FEED FOR GAS LIFT Filed March 29,` 1945 2 Sheets-Sheet 1 Nov.29, 1949 c. M. OLEARY 2,489,665

PNEUMATIC FEED FOR GAS LIFT Filed March 29, 1945 2 sheets-sheet 2 GasSuiv/:ly Pressen-c )Dr-essere L51 7,5 n ,Blow aff/20e opens f f zacloses Patented Nov. 29, 1949 UNITED STATS --PTENT l"Oll'il-Cll PNEUMATCFEED FOR GAS LIFTS Charles M. DLeary, Detroit, Mich.. f

Application Mal'ch '29, 1945Selial N0. 585,473

12 clams.' (ci. 10a-'2321 l v The lpresent invention .relates to meansfor flowing loil wells by gas under ,pressure and resides in Aanimproved form of bottom hole intermitter particularly adapted :for useon large production deep wells. t

Ordinary gas lift installations are not particularly effective on largeproduction deep wells, due to the lfact that the gas pressure requiredat the bottom of the well to lift the column of oil materially retardsinilow yof oil from the formation. In addition, the natural flow rate ofwells varies constantly, with the resul/t that it is difficult todetermine or maintain the optimum gas-oil ratio for owing the well.LAccordingly, attempts have been made to relieve the bottom of the wellfrom the pressure resulting trom the long l'column of oil and gas inlthe outflow tubing and to maintain a constant rate of oil iiow byinstalling iiow chambers in the bottom di the well which are equippedwith --check valves past which oil may flow by gravity to lill thechamber. These chambers are then intermittently blown by gas pressure toforce the `oil up into the oil outflow-tubing without applying thepressure .in the tubing to the formation. In certain of theseconstructions control of the blowoff and lling periods has been achievedby periodically varying the gas pressure supplied to the well at theground surface. This expedient, however, is objectionable because of thelong time required to bui'ld up the ,pressure of the llarge volume ofgas 'in the tubing of a deep well. In addition, 'these prior expedients.have operated to blowr each slug of oil entirely from the wel-l,

with the result that excessive quantities of gas trolled vaivemechanisms have proved Auz'tsat'isfactory for several reasons. In 'the'st place.,

the f ioats are subject 'to `forces resulting 'from the how or surgingof 'gas and oil independent of the oil level. Secondly, the lfloatmechanism is yquickly clogged by wax and foreign matterin the oil; and,nally, if the lioa't `and float mecha' ainism are made suciently largeand heavyjto a.

minimize the nrst two dnieulties, Athey require too much vspace at thebottom of the well and, therefore, cannot be installed or removedwithout removing `all of the oil outflow tubing. Accordingly, it is thegeneral object of the present invention to provide a bottom hole in#termitt'er 'which will periodically blow the oil from the ilingchamber'into'the oil tubing, in which it may be lifted by an auxiliarygas 'supply during the reiilling period, and 'in which the cycle oioperation is controlled by the gas sup' plied'under relatively constantpressure to the bottom of the well through a macaroni or gas tubing.

','Another object of the invention is to provide a mechanism of the typementioned, in which the relative duration of the filling and blowenperiods' may be readily adjusted to accommodate 'the nat' ural flowconditions of the well by adjusting the pressure 'o'f the gas supplied.

" Another 'object of the invention is to provide a mechanism of the type'mentioned which incorporates no mechanism or moving 'parts in con-`tact with the oil except the conventional bali check valves associatedwith the 'ow chamber and which, thereiorecanno`t Vget out of order byreason of accumulations of wax vor foreign materials such as are(present in the liowing oil.y

'Another object of the present invention "1s to provide a mechanism ofthe type mentioned in which all of the operating and control valves areoi the Apoppet or ball check type in which a positive gas pressureoperates to hold them in their closed positions and in which all of thevalve operations are vcontrolled by gas pressure.

Another object o the invention is to provide a mechanism in which allrelatively sliding parts are 'sealed against Contact with gas suppliedto the unit and the oil in the well and tubing. *Y Another object of theinvention is to provide a mechanism of the type mentioned, in which thefrequency of the cycle of operation may be ati-'- jps'ted to a limitedextent by changing the gas sjiipply pressure, and in which the frequencymay' be' adjusted over a 'wide range to suit conditions existing in vanygiven well by very simple ad` jjustments. jjAnother object ofthevinvention is to provide a mechanism of the type mentioned, all portionsof which, except the flow 'chamber itself, 'may andere be Xed to thelower end of the macaroni or gas supply tubing and inserted into orWithdrawn from the oil outflow tubing Without disturbing the latter.

Another object of the present invention is to provide an improved formof valve mechanism for producing a uctuating gas pressure from aconstant pressure source for use in operating a pressure responsivedevice.

Other objects, which include the provision of an intermitter of the typementioned which is extremely rugged, compact, and simple inconstruction, will become apparent from the following speciiication, theaccompanying drawings, and the appended claims. l

In the drawings,

Figures l and 2 are, respectively, sectional viewsf.-

taken through the upper and lower portions or the preferred embodimentof the inventions# Figures 41 5 and 6 are pressurekldiagrams illusftrating the principle of operation of the mecha:

msm.

yReferring to the drawings, anldparticularly Fig-f usilggand 3 tnereoithinprveaintermitter mechanism comprises a, generally cylindrical valveblock I, to the' lower 'end f which is xed an elongated cylindricalshell'2"forming the walls of a now chamber which Vmay be of any desiredlength and which is closed at its lower end by means of a plug 3. Valveblock 2v also `carries a centrallyl located oil now tube '4 whichprojects downwardly into the low chamber and carries at'its lower end ahousing Banda ball check valve 6 which operates to permit free flow ofoil uph-r Wardly through theV tube, but prevents reverse flow. The plug3 is likewise provided with a down` Wardly projecting iniiow oil tubing'I which com" municates with a port 8 in the plug 3. The port 8"iscontrolled by means v4of aballcheck valvev S'positioned with referenceto the port 8 by means o'f a cage I8. This ball check valve 'permitsfree inow of oil through tubing Ito 'the interior of the chamber 2 butprevents reverse flow. The inflow tubing 'l may be of anyde'siredlength, but it"will be' appreciated that tle 'entire chamber 2 must belocated below the natural oil level in the well in order to permit thegravity ow of oil into the chamber past the'y checkvalve 9. *'To theupper end of the valve block I is secured asimilar cylindrical casingII, the upper end of which is threaded, or otherwise suitably secured,to the lower end of the oil outflow tubing I2.

The remainder of the mechanism, which includes the control valves forintermittently blowing the 'chamber 2, is xed to the macaroni or gassupply tubing I3 and may be inserted or removed without 'disturbing theoil tubing I2 and the por' tions of the mechanism carried thereby. Thiscontrol valve mechanism is mounted in an elongated cylindrical chamberI4 which is threaded or otherwise fixed at its upper end to the lowerend of the gas tubing I3, andy which is closed at itsl lower end bymeans ofla conically tapered block I5 that is adapted to seatwithin, andmake sealing engagement withLarcorrespondingly conically tapered recessI6 formed in the upper end of the valve block I. The b1ockI5 is providedwith a'central bore I1 which is adapted to communicate with a passagewayI8 in the Lvalve blocl-ry I, and the latter passageway communicates withthe interior of the chamber 2. The valve block I is provided with anopening I9 in its lower face in communication with the interior of thetube 4.

which in turn communicates at its upper end with a plurality ofpassageways 29 which connect to the space between the housings II andI4. The conical recess I6 in the valve block I is provided with anannular groove 2| which communicates with a port 22 in the valve blockwhich opens to the well space outside the oil outflow tubing, thehousing II, and the chamber 2 at a point above the chamber 2. Thechannel 2! likewise communicates with passageway 23 in the block I5which leads to the space within the housing I4.

The housing I4 is made in three sections, 24, 25, and 26. Sections 24and 25 are connected by means 0f ablock 21, and sections 25 and 26 areconnected by means of a block 28. Block 21 is fixed to an upwardlyprojecting cylindrical housling 29 within the housing section 24,leaving a space 30 between the walls of the housings 24 and 29. `A.cylindrical housing 3I is xed in sealing relation to and between theblocks 21 and 28, withinthe'housing section 25, and the walls of thehousings 3I.and 25 are spaced apart to provide a passageway 32. Thepassageways or spaces 38 anrdc32 are connected through a plurality ofopenings 33 in the block2I, as best shown in Figure 3,-and the space 3Dis inunrestricted 'coni-A mun'icati'n at its upper end with the interiorof theigassupply tubing I3. Block 28 is provided with a side Vport 34connecting the space 32v to. a valve chamber 35 having a gas blowof`valve' 36 controlling a port 31, whichris connected by a plurality ofpassageways. 38, through the block- 28, to the space within a eXiblebellows 39, the upper end of which is i'ixed to the lower face-oftheblock 28. The bellows 39. carries at `its lower end'a plunger in theform of a'valve element indicated generallyat 4G, which is made up of ahol-` low stem 4I and a poppet type head 42, adaptedto co-operate with avalve seat 43 at the upper end of the passageway-I1 in block I5. Thecrosssectional area ofthe valve seat 43 is greater than the-cross-sectional area of the bellows 39, and the opening-44 in thetubular valve stern 4I isl more restricted to the passageways 38 and 23,

454 with the result that any iiow of gas through the' passageway 44tends to elongate the bellows 33 andseat the valve 40.` `The normallength of the' bellows 39 is such as to hold the valve 48 in spaced,relation to the seat 43 when no gas is flowing'l through passageway 44,and the effective area of valve 42fis greaterthan that of bellows 39.`As a` result of the mechanism so far described, it will be apparentthat normally the blowoff valve 36 closes the port 37 in block 2 inresponseT to the pressure of the supply gas, thus shutting oiwow of gasthrough the tubular valve 4i) and causing that valve to unseat, asillustrated in the drawings. Under these conditions, the upper end v ofthe chamber 2 is connected to the low pressure space within'thewell bymeans of passageways I 8, 23, and 22, andnov gas under pressureV isvsupplied to thechamber. l When .the check valve 33 is* forced off itsseat against the gas supply pressure which normally maintains it inaseated condition, gas under Apres-r sure will ow from the gas supplytubing through space 30, passageway 33, space 32, passageway 34,- port.3l, passageway 38, bellows 39, valve 49, and passageways I1 and I8 totheupper end of the ow chamberY 2, and therebyseat the ball lcheck valveA 9and forcing ,any Aoilwithin vthe chamber upwardly past the check valve 6through the tub`-,k ing 4, passageways I9 and 28 tothe space between.,the housingsgl Land I4..` and `thence to the oil out-1 flow spacebetween the oil tubing I2 and the gas ausgabe.

tubing I3. Since, during these conditions, the space within the housingsection 26 is at a lower l pressure than the pressure in passageway I1and bellows 39, and the area of valve head 42 is slightly greater thanthat of the bellows 39, the pressure within the passageway I1 tends tounseat the valve 49. However, a small pressure drop of the gas passingthrough the restricted passageway 44 in the valve overcomes thattendency and maintains the valve in a seated condition so long as thecheck valve 36 is unseated. As soon as the check valve 36 is seated,flow through valve `I stops, and the pressure within passageway I1,which is the pressure within the upper end of the chamber 2, unseats thevalve 49. In this connection it will be noted that the pressure withinthe upper end of the cham-ber 2, when valve 42 tubing. It will beobserved that valves 36 and 42, in combination, operate as a three-wayValve to connect the chamber 2 either to exhaust or to the full supplygas pressure. The particular construction and form of valve disclosed ispeculiarly suited to an oil well insert mechanism because of its in-linearrangement, and has no relatively moving parts, except the poppet typevalves and seats exposed to the gas or oil.

The oil which flows upwardly through the outilow tubing may be lifted'by gas supplied thereto in any desired manner, such as by the smallopening 45 in the lower end of the gas tubing i3. It will be understoodthat any other means for supplying gas to the oil column, including `gassupply valves responsive to the pressure in the oil tubing, may beemployed in accordance with conventional practice.

The ow chamber 2 is entirely immersed in the oil normally standing inthe well to any desired depth except that the external pressure on inletf 8 should not exceed the gas supply pressure inl tubing I3, sinceotherwise the oil would simply flow continuously through chamber 2. Thisis undesirable because there would then be no way of maintaining the oilflow raterconstant, with the result that it would be difficult tomaintainv chamber 2 during the filling period will remain constantregardless of the depth oi immersion of the chamber in the oil since itis a function cf the size of the oil inlet port 8 and the distance (andtherefore the pressure difference) between the port 8 and port 22.

Valve 36 is unseated by means of a stem 46 fixed to a plunger member 41,which is secured to and seals the lower end of an expansible bellows 48.The upper end of the bellows 48 is xed and sealed with respect to thelower surface of block 21 in communication with a passageway 49 throughthe block. A second expansible bellows 50 surrounds the stem 46 and issecured in sealing relation at its ends to the vplunger 41 and the uppersurface of block 28. The effective crosssectional area of the bellows 59is approximately equal to the effective cross-sectional area of the,port 31, and the effective cross-sectional area of the bellows 48 isslightly greater than that of the bellows 50. As a result of thisarrangement, ap-

plication` of pressure to the interior of bellows 48 in an amount lessthan that of the gas supply pressure acting on the bottom of the blowofIvalve 36 will open that Valve, and the blowoff valve is balanced againstthe influence of pressure within the bellows 59 and port 31. The amountof pressure in belows 48 required to open valvev 36 depends upon theratio of the area of the bellows 4B to the port 31, as hereinafterpointed out in greater detail. bellows 59 the pressure in port 31 wouldrise on opening of the blowoif valve 36, and the resulting increasewould tend to move the plunger 41 upwardly and thereby tend to closeblowoif valve 36. This would throttle down the pressure in port 31. Thebellows prevents this throttling action and, therefore, insuresapplication of the full gas supply pressure for 4blowol purposes.

Means are provided for periodically increasing and decreasing thepressure within the bellows 48 at a predetermined frequency in order toalternately fill the chamber 2 and eifect a blowoif of the oil in thelled chamber. This means comprises the aforementioned passageway 49 inblock 21, a lateral bleed passageway 5I connecting passageway 49 to theoil space between housings II and I4 and an intermitter valve 52 forcontrolling the admission of gas under pressure to the passageway 49.The intermitter valve 52 is operated by an intermitter mechanism, themajor portion of which is located within a cylindrical housing 53 xed insealed relation to the upper end of block 21 and provided at its upperend with a small inlet bleed port 54 communicating with the supply gasunder pressure in the gas tubing i3. The cross-sectional area of thebleed port 54 must be smaller than the cross-sectional area of thepreviously mentioned bleed port 5 l as pointed out hereinafter ingreater detail. v Housing 53 is provided intermediate its ends with ablock 55, to the upper surface of which is fixed a cylindrical housing56 containing a plunger 51, which is normally urged downwardly by meansof a spring 58. A stem 59 connects the plunger 51 to a plunger 69, whichis fixed to the intermitter valve 52, with the result that the spring 58normally acts to hold the intermitter valve in closed position. Aflexible bellows 6I is fixed in sealed relation at its ends to theunderside of block and to the plunger 60, with the result that thespring 58, plunger 51, and stem 59 are entirely sealed against contactwith the gas in the housing 53. The block 55 is provided with aplurality of openings 62 providing an unrestricted communication withinthe housing 53, between the space above the block 55 on the outside ofhousing 56 and the space below the block 55 on the outside of thebellows 6|.

The operation of the intermitter valve mechanism is as follows: Gas atsupply pressure in tubing i3 enters the bleed port 54 and graduallybuilds up the pressure within housing 53. This pressure, acting on theunderside of plunger 68, tends to lift intermitter valve 52 off itsseat, and that tendency is resisted by means of spring `59. The strengthof the spring is so chosen with respect to the effective cross-sectionalarea of the plunger 60 and bellows 6I that the intermitter valve 52 isnot opened until the pressure within the housing 53 reaches a pressureslightly below that of the gas supplied in tubing I3. When that pressureis reached valve 52 opens, thus per mitting a flow of the gas within thehousing 53 throughthe passageway 49 of the interior bellows 48.

In the absence of thel It is desirable, although not necessary. t0-

aree/,cos

7"* reducey 'the pressure drop incident 't6-th' filli-"rlgfl bellowsf'litoav minimumand, accordingly, there is illustrated acylindrical'plug 63 fni'ed'to th plunger 41 substantially filling-'thebellows48 to'" reduce 'its volumetric capacity. Once the valvel- 52f`isopened the eective area of th'e plunger v(ill` is increased by the areaof the valve 52 and, consequently, the valve 52 will remain o'pe'untiltheV pressure within the housing 53 drops to a valuer` belowlthepressureat which valve 52 was opened'. It is desirable to keep thedilerence between'thei pressures at which valve 52 opens and closes toa"small value, in the order of 25 to 50 pounds per square inch.

As soon as the valve 52 is opened the -pressure within housing 53,passageway 49, and bellowsr48^ will begin to drop, by reason of theoutflow of Ygas Y through the bleed port. I.4 Since this' bleed portVhas a vlarger effective area than the bleed port 54, the gas will flowoutwardly through port 5| faster than it enters port 54, and result in agraduali reduction in the pressure within the housing 53 and ythebellows 48. After the pressure Adrops to' the point at which valve 52closes, the pressure in bellows 48 drops rapidly7 to the pressureexisting in the space between the housings l I and I4 (the pressure headat the bottom of the oil outflow tubing), and at the same time thepressure within the housing 53 begins to build up by reason of the flowthrough port 54.' It will be apparent that by adjusting the sizes of theports 54 and 5l relative to the volume ofthe gas space within thehousing 53 and the bellows 48, the frequency with which the valve 52opens and closes may be readily adjusted.

. Thus, if the size of opening 54 is increased while all remainingfeatures of the design remain un'- changed, the period of time requiredto build up' pressure in housing 53 will be reduced, and consequentlythe period of time during which the valve 52 is closed will becorrespondingly reduced; and vice versa. By the same token any increasein the size of passageway 5I, all other features of the design remainingthe same, will shorten the period during which valve 52 is open; andvice versa.

The frequency of each complete cycle of operation of the valve 52 forany given pressure in the gas supply tubing I3 is Xed by the strength ofspring 58, the relative effective areas iof v the plunger 66 and thevalve 52, the sizes of bleed,k ports 54 and 5I, and the volumetriccapacity of the housing 53 and the bellows e8. However, for'. any enfrequency for the complete cycle of` `operation vthe relativeproportionsof the fillingv and blowo portions ofthe completecycle maybevaried by varying the relative cross-sectional areas of the bellows 48'and 5D. In, additionfthe relative proportions of the complete cycledevoted to the filling and blowoi periods may also be materially variedfor any given construction by. slight variations in the pressuresupplied to tubing I3. This will be apparent from the pressurev diagramsin Figures 4, 5, and 6 which representdiagrammatically the character ofthe variations in pressure, which result in housing 53 and bellows 48.for one embodiment of the invention.

The pressure diagram of Figure l is based upon the assumptions/that thegas pressure in tubing I3 is 500 pounds per square inch, the pressure atthe bottom of the oil outow tubing is 400 pounds per square inch, andthe intermitter valve 52 and its operating mechanism are so constructedthat the valve opens when the pressure in housing 53 is 475A ppundspersquare inch and closes when thezpressure lsiiprdslfier square inch?YTIihese operati ing conditions are selected more or less arbitrarily andmay bevaried as desired, except that fthnlfflk pr'essure *atl which theinterrriitter valve o pe'nsfi must be something less-than the full gassupply* pressure, andthe pressureat whichthe -intermitel ter valvecloses must be more than the pressure irf'fr* theoiltubing.-4 3" If,with` an intermitter valve lconstructed as above described, `the'outletbleed port 5I has an effectivecross-sectional area approximately three@times that-of the-inlet 54', the pressure in'fthef housing 53, uponclosure of the valve 52, will drop-l along the dottedline 64 until thepressure in 'the' housing53,of 425 pounds per square inch, is reached.Thereuponivalve 52 will close and the' pressurein the housing 53will'rgradually rise, 'as'LL indicated b'y the rising dotted line portion 65,junef'l til l ythe Afpressure again.- reaches "475 ylpounds p'e'rEsquare inch, whereupon the cycle will repeat-itself.,- The time elapseIfor a. complete cycle ofV operation-j ofvalve52,;which#is represented`by the horizontal distance onthediagram Figure 4, determinesA thefrequencyof the complete filling and blowofl cycle of the chamber 2.`While the pressure in the' chamber 53y is iluctuating-in-generalaccordance' with the dotted lines 64 and 65, -the pressure in.I thebellows 48 varies inaccordance with the solidy line` in the samei'lgure. Thus, when valve 52 opens,` the pressure in bellows 48 willrise abruptlyf along the vertical line 63 until it equals the pres-Dsure in housing 53. The pressures in `housing '53l and the bellows48-remain equal throughout the period that valve 52 is open, Therefore,the. pressure in the bellows 28, indicated bythe solidi line portion 66,is identical tothe pressure indi-l cated by the dotted line 64 until thepressurev reaches 425 pounds per square inch, at which the Valve 52closes. From that point on 'the twol -curves depart from each other,since the pressure 1 in housing 53 then rises, while the pressure inthe, bellows 48 continues to'drop even more rapidly-l than before, dueto the outflow of gas through the opening 5I, until the pressure in thebellows 48; equals the pressure in the outow tubing, i. e.,` the spacebetween housings I I and Id. This more, rapid portion of the pressuredrop in bellows 412.,- is indicated by the solid line portion S'I. Assoonv as the pressure in bellows d'8 equals the pres-- sure in theoutowtubing it remains constant'at4 that pressure until;valve 52 againopens and thenimmediately rises, as indicated by the solid straight line68, to approximately the pressure in-v housing 53 at the time valve 52opens.y This comf pletesthe pressure cycle in the bellows I135,- and.vthat cycle repeats itself in the same manner. ,z -g Given the pressurecurve indicated in solid lines'.4 in Figure 4 for bellows48, itxisapparent that the duration of the blowoff vperiod may be varied withreference to the duration of the complete cyclej by varying the pressurein bellows 4.8 at which the blowo valve 36-is opened. Thus, as indicatedirf; the drawing, if thecross-sectional area of the bellows48 is of suchsize with respect to the area; of port 3l that apressure in bellows 4'8of 43"#Y pounds per square inch will open the valve 36,1the duration ofthe blowoff period will be representedy by the length of the dotted line69 between its; points of intersection with kthe solid lines 68 and, 64,and the duration of the filling period willbe. the remainder ofthecycle.- Thus, if the duration, of the complete cycle, as illustrated inFigure 4,. istwelve seconds the Yblowoil period will be-'three seconds,and the filling period nine seconds. Ivfon thbeothlec handthe blowoilvalve was, onfv structed to open at a lower pressure, the blowoff periodwould be lengthened at the expense of the filling period. Accordingly,for any given pressure curve for bellows 48, the pressure in bellows 48at which the valve 36 opens must be so chosen for any given installationas to provide the requisite illling and blowoif periods. In the examplegiven, therefore, the size of the inlet opening of the chamber 2, thecapacity of the chamber, and the distance between the inlet opening 6and the outlet opening 22 must be such that the chamber will completelyfill in nine seconds. Since the rate of filling is determined entirelyby the'distance between the openings 6 and 22, the size of the opening 8and the capacity of the chamber, the rate of filling of any givenunitwill remain constant regardless of the depth to which it is immersed inthe oil standing in the well.

Likewise, in the example given, the rate of blowoii' of the oil from thechamber must be completed in three seconds. This is controlled by thedifference in pressure between the gas supply and the pressure in theoil tubing, the size of the oil outletpassages I9 and 20 and the volumeof oil in the chamber. These factors may be so correlated as to providea complete blowof in the blowoff period available.v If, for any reason,a greater proportion of each cycle is required for blowoif and less forvfilling it is only necessary to reduce the pressure at which the blowoffvalve opens to achieve that result, l

It will be observed that the mechanism so far described provides a meansfor maintaining a uniform feed of oil to the oil tubing regardless Y.

of variations in the natural level of the oil in the well. Consequently,it is possible to maintain, by means of a constant flow'of lift gasthrough the bleed opening 45, or otherwise, the ideal gas-oil ratio toproduce the most efficient gas lift conditions in the oil outiiowtubing,v and there is no possibility of this ratio being upset by surgesof variations in the oil ow. In addition,` the rmechanism entirelyrelieves the oil formation of the pressure necessary to lift the gasthrough the oil outflow tubing and, conse'- quently, materiallyincreases the production of the well over conventional gas liftarrangements.

An important feature of the invention resides in the fact that therelative portion of each l complete cycle which is devoted to blowoffand/or the filling period may be materially adjusted by small changes inthe pressure of the gas supplied through tubing I3. The effect ofsuch'changes upon the performance of the apparatus depends upon therelative sizes of the openings 5| and 54. If the size of those openingsis such that the pressure cycles approximate those illustrated in Figure4, it is possible, by small adjustments in the gas supply pressure tovary the blowoif period without any appreciable change in the lillngperiod. This arrangement is advantageous, since the lling rate may be-more easily controlled by the design and construction oi?l the chamberand, being usually a longer period than the lblowoff period, is lesssensitive to small vari ations. Moreover, the eiliciency of the unit isless seriously affected by a filling period `which is slightly too longor too short than by a blowoff period which is tooV long.

The manner in which the above mentioned adjustment in the blowoiT cycleis achieved is illustrated diagrammatically in Figures 5 and 6, in whichFigure 5 shows the effect of an increase in the gas supply pressure to510 pounds per square inch, and Figure 6 shows the effect of a decreasein the gas supply pressure to 490 pounds per square inch for the unit,the performance characteristics of which are illustrated in Figure 4.

Referring to Figure 5, it will be seen that the dotted line 10 and thesolid line ll, which represent, respectively. the pressure droppingcurves for the housing 53 and the bellows 46 after the intermitter valve52 opens, have a slightly more gradual slope than d o the correspondinglines 64 and 66 in Figure 4, due to the fact that the slight increase ingas supply pressure increases the quantity of gas which enters port 54during the period that valve 52 is open. Likewise the dotted line 12,which represents the ascending pressure curve for housing 53 when thevalve 52 is closed, is steeper than the corresponding line 65 for thesame reason. One result of the pressure change in the illustrateddiagram is a slight reduction in the period required for the completecycle. In addition, the increase in gas supply pressure, which iseffective on the underside` of valve 36, results in an increase ln thepressure in bellows 48 necessary to open the valve 36. This increase isrepresented by the higher position of the horizontal line 13 whichrepresents the pressure in bellows 48 at which the blowofi valve 36opens and closes. As a result of the increase in the height of line 63,as compared with the'height of the corresponding line Ilill in Figure 4,the blowoff period is reduced from three seconds to two and one-halfseconds. However, since the complete cycle was slightly shortened thefilling period remains approximately the same, or about nine seconds.The slight decrease in the period for the complete cycle, which resultsin an increase in the frequency of the cycle, slightly increases therate of flow of oil to the outiiow tubing, thus compensating for theadditional supply of lift gas which will be supplied through port 45 asa result of the increase in gas supply pressure.

The blowoil period may be similarly increased, as compared withv thatrepresented in Figure 4, by reducing the gas supply pressure to 490pounds. Thus, as shown in Figure 6, the reduc tion in gas supplypressure reduces the pressure in bellows 48 required to open the blowoi!valve 36, as indicated by the lower position of the horizontal line 14as compared with the corresponding line 69 in Figure 4. This increasesthe blowofl period to three and one-half seconds. In this case thereduction in gas supply pressure slightly increases the period for thecomplete cycle and' consequently the filling period remainssubstantially the same, or about nine seconds. The slight reduction inthe frequency of the cycle resulting from the reduction in gas supplypressure reduces the rate of flow of oil to the oil outflow tubing tocompensate for the reduction in lift gas, which will result from thelower gas supply pressure.

It is apparent from the above that a final adjustment of the blowoffperiod may be readily made after the mechanism is positioned within thewell, by making a small adjustment in the gas supply pressure.Consequently, it is possible to so control the operation of themechanism by the gas supply pressure as to insure optimum blowoiconditions.

While, as indicated above and illustrated diagrammatically in Figures 4,5, and 6, it is possible to so construct the mechanism as to permit avariation in the blowoff period without any appreciable change in thelling period by suit- -121 ablyproportioning*the openings 5l andpityisAlikewise pc,ssib1e,'byjchanging the .relative sizes ofthev openings 5L!and .5 74,.to provide a unit l,in which a reduction in 'blowoi periodincident to ,changes in the gas supply. pressure will result in a'morfeor less corresponding. increase in the lling period, and viceversa. This can be accomplished, V: for example, by decreasingthe sizeof theopening 5l so that the opening of theintermitter valve ,isrdelayed to a greater extent than that illustrated'in Figure/l. It willbe understood, however, ,thatin allrcases Athe Yopening 5| mustbe largerlthan-the opening .54. "'It willv also beappreciated vthat the frequencyof. .-the.1 cycle maybelchanged by changing the will not rise and fallin straight lines, as indicated .on the drawings, and as a practicalmatter' the 'proper sizes for the bleed openings 5| and 54, as `bestdetermined by trial for any given installation. Since the openings Yarer formed in removable plugs, it is a simple matter to substituteplugs 3 0 having-openingsiof different sizes. In this manner'anyjdesired frequency andthe character of pressure cyclesmay be establishedin the eld beforethe unit is yinstalled. in the well.

12 `4AT gas, operated bottom hole,inter1nitter,. f.or thel uplift of oilthrough an oil tubingby'ga's under ,pressure in a gas .tubing associatedwith vsaid `oil tubing, comprising' an oil chamber having nlet andoutle'tbil passages adapted to communicate respectively withthe oilstanding in tle'well and the .interior oithe oil tubing, a gas pressurepperated valvelmechanism for controlling thefgas pressure intheoilchamber, said mechanism .including a gas chamber and being effectivewhen the gas pressure insaid gaschamber is atone valueto,admitIgas'hunder pressure to saidjoil chanibentodischarge oiltherein andbeing'eietive when the gas pressure in said gaschavmber is at ,alloy/'errvalue tp v.disconnect the oil chamber from the gas tubing 'to permitgravity llinggfof saidioil chamber, and pneumatic means kadapted to beconnected to the lower endof the gas tubing to elect a periodicjfluctuationdinthe gas pressure lin saidigclambenfrom a relativelyconstant pressuregas supply lin the gas tubingrfrom vone ,of saidtwopressures'to the other, said pneumatic nieansinludingnmeans providinga lbleed passage I',ijm...tl-1e,lower endofy the gas tubing into the gaschamber and meansfproviding Va restricted pas,- fsagewofmlarger sizethan said bleedpassage and cfonnecting the gas chamber to thelowerrrendj'oi thejil tubing and a `,valveloperabl'e' to open saidgtriete'djlpassag'e only whenthe pressurein ,the ygas, chamber reachessaidone'value. l' A '2.' A",gas ,operated bottom hole intermitter forI,tliejfiplliit of oil through anoil tubing bygas ,underf lressurein`a"g'as` tubingvassociated with An important'feature of the .inventionresides 3.5

iny the' fact that all portions'of theimechanism, .except the fillingchamber itself and the ltwo check valves associated therewith, is `fixedto and `removableasa. unit with the macaroni or gas tubing I3,andco'n'sequently, may be removed from A.the well without disturbing theoil tubing. It is thus a relatively simple matter to remove themechanism for repair` or adjustment.

Another 'important feature lof the invention resides inthe fact that allof lthe relatively slid- .ing parts are entirely sealed againstconta'ctwith either` oil or gas.- It is for this'reason that bellows`- areemployed in connection with Ithe three valves 52,35, and 42..'7It-willbe Vappreciated(,that

from affurictionalY standpoint v ordinary piston operated plungers wouldservethe same purpose as the bellows but would,vof course, involverelaltive-slidingmemberswhichfare in Contact with the-gas and hencemaybecome vcontaminated or 'clogged by waX and other accumulations. ,fItwillbe understoodvthat theproportions of the mechanism,as shown in thedrawings, are distorted to facilitate:illustratin. lztiiall'y themechanis'mv'shuld be muchY longer, as compared With-its diameter,thanappears from the drawing.' Thus the Vlling chamberrnay be anydesired length up to several hundred feetL depending upon thevheight ofthelnlatur'al 'oil'level in the well and the rate of production.' All ofthe expansible 'bellows' employed in the valve `mechanism should bematerially/'elongated to reduce the stresses thereondue'rto the smallmovement required to operate'the valves, and the gas exl haust outlet'22y is preferably located fat a substantial distance above,V the topfotthe. lling chamber in order to 'reduce 'the enhaustpressure and therebyincrease'the` filling rat f 'the chamber' f "l; ..Q c

' what is claimed ',Saidif'oftubing, Vcornprisinga chamber having,inlet"and outlet oil passagesV adaptedto communicat respectively' 'withthe foil standingin 'the vwe1'1 and une interior of the eil tubing,cheek valves,`A in said Vpassageways, meansv forming a 1rd..passagewayconnecting the chamberv at. ,a pom't above v'said inlet withfthe low pressure :space outside saidoilfand gasv tubings, said thirdpss'age-w'ay including a valve seat, a member having a gasl supplypassage-adapted to-receive gas from vthe lower end `of the gas tubing, aflow responsive valve-member adapted toV engage said valveseat, saidvalve member having an opening Ytherethrough communicating with said gassup- I.ply-,passage whereby said Valve is seated by llow from' said Ygassupply passageV through said .'Valve,land whenlsoseated connects saidgas supplypassage to saidrst chamber, said valve when seatedbeing'elective to block` ow from said fstjchambertmsaid lowy pressure space,`and lmean'sdor periodically supplying gas under pressure :to .said Agasvsupply rvpassage from said gas Ltub'ing to cause said valvetoperiodically engage saidseat.: -f I -y 31A gas operated bottom holeintermitter.y for the .uplift of oil throughr anloil tubing by gasvunder pressure in a gasltubing associated with ,said oiltubing,comprising-a chamber having inlet and outletroil passagesadapted tocom-A municatefyrespectively with the oilv standing in .thec-well'andtheinterior of the' o iltubing, check valves. .in said passageways, meansforming 'a ,third passageway connecting the chamber at a ,point abovesaid inlet with the low pressure space ,outside said. oil and gastubings, said third 'passageway including Viau/valve seat,- a valveadaptedto eng-age saidseat and thereby block .dow through saidpassageway between the chamber and said low pressure space, anexpanslble ,bellows having one end fixed to said valve in,axialalignment therewith, a support for the upposite'end ofthegbellows, said valve and sup-l port having openingsV communicatingwith the interior of said bellows, and means for periodically supplyinggas under pressure to said opening insaid support from said gas tubingto cause said valve to periodically engage said seat, said valve andseat being so arranged that when the-valve is seated the gas supplied to.said support opening flows through said bellows and said valve intosaid chamber and such now holds said valve seated.

4. A gas operated bottom hole intermitter for the uplift of oil throughan oil tubing by gas under pressure in a gas-tubing associated with saidoil tubing, comprising a chamber having inlet and outlet oil passagesadapted to -communicate respectively with the oil standing in the welland the interior of the oil tubing, check valves in said passageways,means forming a third passageway connecting the chamber at a point abovesaid inlet with the low pressure space outside said oil and gas tubings,said third passageway including a valve seat, a valve adapted to engagesaid seat and thereby block flow through said passageway between thechamber and said lowfpressure space, an expansible bellows having oneend fixed to said valve inaxial alignment therewith, a support for theopposite end of the bellows, said valve and support having openingscommunicating with the interior oi said bellows, said valve and bellowsassembly including resilient means norvmally tending to disengage saidvalve from its seat, and means for periodically supplying gas underpressure to said opening in said support from said gas tubing to causesaid valve to periodically engage' and disengage said seat, said valveand seat being so arranged that when the valve is seated the gassupplied to said support opening flows through said bellows and saidvalve into said chamber and such flow holds said valve seated.

5. A gas operated bottom hole intermitter for the uplift of oil throughan oil tubing by gas under pressure in a gas tubing associated with saidoil tubing, comprising a chamber having inlet and outlet oil passagesadapted to communicate respectively with the oil standing in the welland the interior of the oil tubing, check valves in saidY passageways,means forming a third passageway connecting the chamber at a point abovesaid inlet with the low pressure space outside said oil and gas tubings,said third passageway including a valve seat, a gas supply passage, aflow responsive valve member adapted to engage said seat, said valvemember having an opening therethrough communicating with said gas supplypassage whereby said valve is seated by flow from said gas supplypassage through said valve and when so seated connects said gas supplypassage to said first chamber, said valve when seated being effective toblock flow from said first chamber to said low pressure space, and meansfor periodically supplying gas under pressure to said gas supply passagefrom said gas tubing to cause said valve to periodically Aengage saidseat, a second valve for controlling said gas supply passage, andpressure operated means for periodically opening and closing said secondvalve including -a second chamber communicating with said means, saidsecond chamber having a restricted inlet communicating with said gastubing and an outlet having less restrictive effect than said inlet, athird valve for controlling communication between said inlet and outletof the second chamber, and means operable in response to a predeterminedpressure in said second chamber for opening said valve and eilectivewhen the pressure drops to a lower value to close said valve.

6. A gas operated bottom hole intermitter for the uplift of oil throughan oil tubing by gas under pressure in a gas tubing associated with saidoil tubing, comprising a chamber having inlet and outlet oil passagesadapted to communicate respectively with the oil standing in the welland the interior of the oil tubing, check valves in said passageways,means forming a third passageway connecting the chamber at a point abovesaid inlet with the low pressure space outside said oil and gas tubings,said third passageway including a valve seat, a valve adapted to engagesaid seat and thereby block flow through said passageway between thechamber and said low pressure space, an expansible bellows having oneend fixed to said valve in axial alignment therewith, a support for theopposite end of the bellows, said valve and ysupport having openingscommunicating with the interior of said bellows, said valve and bellowsassembly including resilient means normally acting to disengage saidvalve from its seat, a fourth passageway connecting said opening in thesupport with the gas tubing, a second valve for controlling the fourthpassageway, and pressure operated means for periodically opening andclosing said second valve including a second chamber communicating withsaid means, said second chamber having a restricted inlet communicatingwith said gas tubing and an outlet having less restrictive effect thansaid inlet, a third valve for controlling communication between saidinlet and outlet of the ysecond chamber, and means operable in responseto a -predetermined pressure in said second chamber for opening saidvalve and effective when the pressure drops to a lower value to closesaid valve.

7. A gas operated bottom hole intermitter for the uplift of oil throughan oil tubing by gas under pressure in a gas tubing associated with saidoil tubing, comprising a chamber having inlet and outlet oil passagesadapted to communicate respectively with the oil standing in the welland the interior of the oil tubing, check vvalves in said passageways,means forming a third passageway connecting the chamber at a point abovelsaid inlet 4with the low pressure space outside said oil and gastubings, said third passageway including a valve seat, a valve adaptedto engage said seat and thereby block flow through said passagewaybetween the chamber and said low pressure space, an expansib-le bellowshaving one end xed to said valve in axial alignment therewith, a supportfor the opposite end of the bellows, said valve and support havingopenings communicating with the interior of said bellows, said valve andbellows assembly including resilient means normally acting to disengagesaid valve from its seat, a fourth passageway connecting said opening inthe support with the gas tubing, a second valve for controlling thefourth passageway, and pressure operated means for periodically openingand closing said valve including a second chamber communicating withsaid means, said second chamber Ihaving a restricted inlet communicatingwith said gas tubing and an outlet having less restrictive effect thansaid inlet, a third valve for controlling communication between saidinlet and outlet of the second chamber, means operable in response to apredetermined pressure in said second chamber for opening said valveandv eiective when the pressure drops to a lower value Ato"clo'se;saidvalve, said last meansincluding a flexible'bellows in said secondchamber having fone end connected to the third valve, a support for theother end of said bellows, the cross-sectional area of said bellowsbeing greater than the effective area of said valve, the space withinsaid bellows being completelyy sealed from the space `Within saidchamber, and means resiliently urging said valveltoward closed position.

8."A gas operated bottom hole intermitter for .".the uplift ofoilthrough an oil tubing by gas runder pressure in a gas tubingassociated with said oil tubing, comprising a chamber having in- Vletand outlet oil passages adapted to communi- "cate vrespectively with theoil standing in the .ifwell and the interior of the oil tubing, checkvalves in said passageways, means forming a third passageway connectingthe chamber at a point above 'said inlet with the low pressure spaceoutside said `oil vand gas tubings, said third passageway in- ;cluding avalve seat, a valve adapted to engage said seat and thereby block flowthrough said rpassageway between the chamber and said low pressurespace, an expansible bellows having one endxed to said valve in axialalignment therewwith, asupport for the opposite end of the bellows, saidvalve and support having openings communicating with the interior ofsaid bellows, .said valve and bellows assembly including resilient meansnormally acting te disengage said rvalve from its seat, a fourthpassageway con- :necting said opening in the support with the gastubing, a second valve for controlling the fourth passageway, andpressure operated means for --periodicallyopening and closing said Valverincluding a second chamber communicating With svaid means, a thirdchamber having a restricted rvinlet communicating ywith said gas tubing,a port v,connecting the second and third chambers, a third valve forcontrolling said port, said port Ywhen open offering less restriction togas flow than said inlet opening for the third chamber, an-outlet forthe second chamber communicating with a low pressure region in said welland hav- ,ing a, restrictive-eiect intermediate that of said thirdchamber inlet and said port, and means Vfoperable in response to apredetermined pressure in said second chamber for opening said thirdvalve and eflective when the pressure drops to a lower Value to closesaid valve.

9. A gasoperated bottom hole intermitter for Lthe uplift of oil throughan oil tubing by gas un- `der pressure in a gas tubing associated withsaid pil tubing,vcomprising a chamber having inlet and outlet oilpassages adapted to communicate respectively with the oil standing inthe well and the interior of the oil tubing, check valves in saidpassageways, means forming a third passageway connecting the chamber ata point above said inlet with the low pressure space outside said oiland gas tubings, said third passageway including a valve seat, a valveadapted to engage said seat -and thereby block flow through saidpassageway 'between the chamber and said low pressure space,

`an expansible bellows having one end fixed to Isaid valve in axialalignment therewith, a support for the opposite end of the bellows, saidvalve and support having openings Vcommunicating with the interior ofsaid bellows, said valve and bellows assembly including resilient meansnormally acting to disengage said valve from its seat, a fourthpassageway connecting said opening in the support with the gas tubing, asecond valve for controlling the fourth passageway, and pressureoperated means for periodically opening :and closing said valveincluding a second'chamber' communicating with said means, a thirdchamber -having a restricted inlet communicating with said gas tubing,'aport connecting the second and third chambersa third valve' forcontrolling said .port,lfsaid-port when open offering less restrictionto gas ow than said inlet opening for thethirdchamber, an outlet `fortheseczond chamber communicating with a low pressure region in said welland having a restrictive eiect 4intermediate that of said third chamberinletv -and Asaid port, means operable in response to-a predeterminedpressure in Vvsaid second chamber for opening said third valve andeffective when the pressure drops to alower value to close said valve,

" :said ,last means including a exible bellowsf in saidthirdchamberlhaving one end connected to the third valve, a support fortherother end of said bellows, the cross-sectional area of said bellowsbeing greater than the effective area ofy said `thirdval-va thespace`within said bellows ybeing `completely sealed from the-space withinlsaid third chamber, and, means resiliently urging said valve towardclosed position. s l

10l -A'gas operated-bottom hole intermittergior the uplift of. oilthroughan oil tubing by gas under pressure in a gas tubing associatedwithsaid oil tubing, comprisingfachamber xed to the oil .tubing andhaving.. an inlet communicating with the oil standing in-lthewell; saidchamber having a top closure wall :provided with apassagetherethroughfor the flowofoil into said oil tubing, an outflow. tube in4 said;chamber connecting/said oil passage to the lower portion of the-chamber,agas ow passage,throughl said wall, a lthird passage connecting.-thespace above said ywall with the spaceoutside-said-oil tubing, v'and -agas supply valve mechanism fixed to the gastubing Tandremovabletherewith independently ofl ,the oil-tubing, said `mechanism.including-means to alternatively supply gas under pressure-to=said gaslflow passage and then connect said gas flow passage to saidthirdpassage. fr

.1 11.'A- gas-operated-bottom hole intermitter I or .the upliftA of oilthrough'an-oil tubing by gas under pressure in a gas tubing'associatedwith said ,oil tubing-comprising a chamber Xed to the oil tubing andhaving f anginlet communicating with theoil standing in the well, saidchamber having a top closurelwall provided with a passage therethroughfor the flow of oil into said oil tubing, an outflow :tubeinsaid`chamber connecting said oil passage to the lower portionof the chamber,a gas flow passage through said wall, a third passage connecting-thespace vabove said wall ,with the space outside said oil tubing, and agas supply valve mechanismv xed to ythe gas tubing and removabletherewith independently of the oil tubing, said mechanism includingmeans to alternatively supply gas under pressure to said gas flowpassage, then connect said gas flow passage to said third passage, andcheck valves in said oil inlet and said oil outflow passages.

12. A gas operated bottom hole intermitter for the uplift of oil throughan oil tubing by gas un- Ader pressure in a gals tubing associated withsaid l'oil tubing, comprising a chamber fixed to the oil tubing andhaving an inlet communicating with the oil standingv in the well, saidchamber having a top closure wall provided with a passage therethroughfor the flow of oil into said oil tubing, an outflow tube in saidchamber connecting said oil passage to the lower portion of the chamber,a gas flow passage through said wall, a third passage connecting thespace above said wall REFERENCES CITED The following references are ofrecord in the le of this patent:

Number UNITED STATES PATENTS Name Date Pohle Aug. 10, 1886 MakinsterOct. 13, 1931 Clark Apr. 27, 1937 Stephens et al, Jan. 3, 1939 CritesJan. 3, 1939 Jennings Jan. 3, 1939 Watson Jan. 23, 1941 Benard Deo. 25,1945

